The invention relates to X-ray powder diffractometers having a monochromatic X-ray source; a detector with position or location sensitive behavior; a mechanism with digitally controllable advance drive for an advance of the detector along an arc suited for the Guinier Method for transmission and/or back reflection beam geometry; and an electronic analysis system for preparing an intensity diagram of the intensity distribution of the diffracted radiation along the diffraction angle 2 Theta. The main components are an amplifier/ discriminator module which delivers a time signal corresponding to the position-location of the respective elementary event in the detector, a time-digital converter, a digital adding module, and a multichannel analyzer.
In X-ray powder diffractometry the Guinier Method is one of the most widespread diffraction measuring techniques. Further details regarding the Guinier Principle can be learned from the book of H. Neff "Grundlagen und Anwendung der Rontgenfeinstrukturanalyse", Oldenburg-Publisher, 1959, particularly pages 160 through 171, incorporated herein by reference. The Guinier Method uses a monochromatic X-ray beam, such as copper K.alpha..sub.1 radiation, and a precise focusing arrangement consisting of a monochromator, sample and detector. The Guinier Method is suitable for plots in the entire interference angular range. Due to the use of strictly monochromatic radiation very low background diffraction patterns are obtained, whereby the detection of very weak interferences is possible which will be lost in normal techniques.
However, a disadvantage of this method is the relatively long measuring time since the primary monochromator supplies only a low beam yield for the measurement.
An increase in the measuring speed can be achieved by a more sensitive detection system, a position sensitive X-ray detector. In existing systems either photographic films or non-position-sensitive X-ray detectors, such as scintillation counters, in conjunction with a fine measuring slit rotating along the Guinier focusing circle have been employed to monitor the diffracted radiation distribution.
In U.S. Pat. No. 4,144,450, incorporated herein as reference, an automatically controlled powder diffractometer is described which, by means of a linear position sensitive proportional counter tube, can increase its slewing speed by about 2 orders of magnitude so that the scanning times can be reduced to less than five minutes. It is here provided that the detector is continuously nonintermittently moved i.e. there is no relevant step movement of the advance along the measuring arc noticeable. In addition, a software system is employed to analyze and interpret the powder diagram.